1. Field of the Invention
The present invention relates to an endoscope system capable of extracting blood vessels, such as superficial blood vessels and medium-deep blood vessels, from a subject, a processor device of the endoscope system, and an image processing method.
2. Description of the Related Art
In recent medical treatment, diagnosis or the like using an endoscope apparatus has been widely performed. As observation of the inside of a subject using an endoscope apparatus, not only normal observation to observe the subject's inside in its entirety but also special observation to observe a specific part on the subject when the specific part needs to be enhanced has been performed.
In the aforementioned special observation, determination regarding whether or not cancer is present from the shape of a highlighted blood vessel is performed. Types of blood vessels mainly include superficial blood vessels distributed on a living tissue surface and medium-deep blood vessels located below the superficial blood vessels. Depending on the purpose of diagnosis, diagnosis may be performed focusing on certain blood vessels. In this case, if blood vessels that are not the focus of observation are added in an endoscope image, diagnosis may be interrupted by the blood vessel. For this reason, differentiating superficial blood vessels or medium-deep blood vessels from the image and displaying an image, which is obtained by extracting only blood vessels to be observed, on a monitor has been demanded.
Regarding the method of determining the depth of a blood vessel, JP2011-135983A discloses a method of performing determination as a superficial blood vessel when the hue of a narrowband image generated based on narrowband light in a specified wavelength region (415 nm, 540 nm) is 5 to 35 and performing determination as a medium-deep blood vessel when the hue is 170 to 200.